This invention relates to a system for use in the irrigation and aspiration of open site surgery. More particularly the invention relates to an electronic control system embodying logic circuitry for the fail safe control of aspiration in combination with open site surgery particularly such surgery which employs ultrasonic or similar surgical tools for disintegrating tissue. One such surgical embodiment and procedure is disclosed in U.S. patent application Ser. No. 555,474 filed Mar. 5, 1975 for Neurosonic Aspirator and Method, wherein apparatus and method are shown for performing ultrasonic open site neurosurgical procedures. As part of such procedures the operative site is open to atmosphere in contrast to a generally accepted ultrasonic operative surgery for the removal of a cateract from the eye wherein the eye is the operative site and is essentially a closed operative site.
In the aforementioned systems, aspiration is an important feature of the operative procedure. By aspiration, what is conventionally meant is withdrawal of fluid from the operative site and more specifically withdrawal by suction of fluid. As such, aspiration is the result of suction applied through a small tubular opening and is so defined herein regardless of whether the suction is applied to an operative site such as the interior of the anterior capsule of the eye as in closed site surgery or from an open operative site where pressure gradients are not critical to the surrounding tissue or from a solution of sterile fluid for clearing the aspiration system.
In the prior art the aspiration system was controlled within certain critical pressure limits which were necessary for operations on the interior of the eye. However, for open site operative surgery, aspiration need not be controlled for purposes of obtaining a specific vacuum pressure and flow withdrawal rate, but aspiration is essential for keeping the view of the surgeon clear to assist him in effectively maintaining contact of the tissue and operative tool tip during ultrasonic vibration of the tool.
In this regard it is advantageous to automatically apply aspiration when the ultrasonic tool is activated. However aspiration is also generally useful without ultrasonic activation of the tool, as for instance to remove fluid and material from the operative site. (One would therefore suppose that aspiration may be continually operated. However it is necessary to release tissue which is not to be disintegrated with the ultrasonic tool). In prior art apparatus, separate switching modes were provided to separately allow aspiration alone or aspiration together with ultrasonic activation of the tool. In either case the aspiration mode is continually activated and deactivated. Such a mode of operation required the operator, realistically the surgeon, to select the desired mode and then operate the appropriate switch. Additionally since suction was obtained by using an electrical motor-driven pump to apply a vacuum, the motor is continually being turned on and off during operation. Such constant on-off switching of the motor subjects the electrical power switches to severe contact loading and the pump seals to continual uneven stress. Wear is particularly aggravated if the vacuum is retained (by tight seals) in the aspiration system resulting in added starting load on the pump motor.
Therefore it is an object of this invention to provide a fail-safe control system for operative surgery embodying aspiration;
It is still another object of this invention to provide an automatic control system for venting and applying aspiration in a surgical operating apparatus;
Yet another object of the present invention is to provide improved apparatus embodying simplified controls and improved reliability;
Still another object of this invention is to provide surgical aspiration apparatus having versatility, reliability and override capability;
Another object of the present invention is to provide an aspiration system having a self-cleaning capability.
Other objects and advantages of this invention will become apparent from the drawings and description of the preferred embodiment which follows.